There is an urgent need to train investigators who have the quality and breadth of experience necessary to conduct transdiscipinary tobacco use research. Although there is no agreed upon model for training transdisciplinary scientists, important components include a rich institutional environment (e.g., physical proximity among trainees, mentors, and collaborators from diverse disciplines), a transdisciplinary curriculum (e.g., opportunities to acquire core attitudes, values, and beliefs, knowledge in scientific approaches, and methodological expertise), and competencies (i.e., attitudes, knowledge, and skills). Essential attitudes, knowledge, and skills are gained through course work, seminars and workshops, mentoring relationships, research experience, interactive groups, and a supportive institutional environment. The overall goal of the University of Pennsylvania's Transdisciplinary Tobacco Use Research Center (TTURC) Training Core is to provide transdisciplinary training in tobacco use research and practice for post-doctoral fellows and medical residents. The primary specific aims are: (1) To recruit and train 3 post-doctoral fellows who are dedicated to developing a career in transdisciplinary tobacco use research. This will be accomplished by providing a co-mentored training experience (with each mentor from a different discipline), as well as formal didactic experiences and independent (mentored) research; (2) To integrate training in tobacco use research in existing fellowship programs at PENN. This will be done via workshops and didactic experiences supplemented by individual mentored research experiences; and (3) To facilitate cross-training in tobacco research of current faculty at PENN through seminar series, tobacco affinity groups, and the submission of manuscripts, pilot projects, and grant applications. A secondary aim will be to integrate didactic coursework in tobacco use research into the required curricula for medical residents at PENN (internal medicine, family medicine, and psychiatry) in an effort to affect tobacco research as well as clinical practice.